Answer this question truthfully
### Question: What causes Mental retardation?
### Response: Mental retardation affects about 1 - 3% of the population. There are many causes of mental retardation, but doctors find a specific reason in only 25% of cases.
A family may suspect mental retardation if the child's motor skills, language skills, and self-help skills do not seem to be developing, or are developing at a far slower rate than the child's peers.
Failure to adapt (adjust to new situations) normally and grow intellectually may become apparent early in a child's life. In the case of mild retardation, these failures may not become recognizable until school age or later.
The degree of impairment from mental retardation varies widely, from profoundly impaired to mild or borderline retardation. Less emphasis is now placed on the degree of retardation and more on the amount of intervention and care needed for daily life.
Causes of mental retardation can be roughly broken down into several categories:
Infections (present at birth or occurring after birth): Congenital Cytomegalovirus Congenital rubella syndrome Congenital toxoplasmosis Encephalitis HIV infection Listeriosis Meningitis
Chromosomal abnormalities: Chromosome deletions (such as cri du chat syndrome Chromosomal translocations (a gene is located in an unusual spot on a chromosome, or located on a different chromosome than usual) Defects in the chromosome or chromosomal inheritance (such as fragile X syndrome, Angelman syndrome, Prader-Willi syndrome) Errors of chromosome numbers (such as Down syndrome)
Environmental: Deprivation syndrome
Genetic abnormalities and inherited metabolic disorders: Adrenoleukodystrophy Galactosemia Hunter syndrome Hurler syndrome Lesch-Nyhan syndrome Phenylketonuria Rett syndrome Sanfilippo syndrome Tay-Sachs disease Tuberous sclerosis
Metabolic: Congenital hypothyroidism Hypoglycemia (poorly regulated diabetes) Reye syndrome Hyperbilirubinemia (very high bilirubin levels in babies)
Nutritional: Malnutrition
Toxic: Intrauterine exposure to alcohol, cocaine, amphetamines, and other drugs Lead poisoning Methylmercury poisoning
Trauma (before and after birth): Intracranial hemorrhage before or after birth Lack of oxygen to the brain before, during, or after birth Severe head injury
Unexplained (this largest category is for unexplained occurrences of mental retardation)